Powell described a series of tests of oscillating razors that indicated that vibrations extended hair sometimes as much as 83 microns, depending on the type of blade used. One micron equals approximately 0.00004 inch.Of course, there's more than one expert being called to testify.
The M3P, according to Powell, extends hair approximately 32 microns, but he admitted he has never tested the current model being marketed, and his figures are based on a prototype.
The Gillette lab also ran tests to see if the way people prepare to shave affects hair extension. The tests showed that just about any time moisture is added to the skin, hair exposure is decreased, most likely because skin soaks up the moisture and hides some of the hair, Powell said. However, when a person rubs his or her face for 20 seconds with a dry finger, hair extends 19.8 microns, according to the tests. But Powell noted that shaving without moisture would be "excruciating." Powell also showed off some of his lab's technology.
Powell wasn't the only scientist questioned Wednesday. John Thornton, an independent statistical consultant who analyzed results from tests that Schick ran on the M3P to see if it performed as Gillette claimed, testified that the data revealed that "there was no significant statistical change in hair length with power on or power off."It's amazing how much money is involved in something so small. The "hair-lengthening" effect that Gillette is advertising is measured with a microscope, but it's worth untold millions of dollars to the company.
But Thornton admitted that his conclusion is derived only from the test data he was given, and that one couldn't conclude that the M3P doesn't extend hair.
For comparison, hair for most people tends to grow about 200 to 400 microns per day, most of the time (as an estimate).